Historically, the valve and valve drive mechanisms have been the least reliable part of the engine assembly. Today, despite roughly half a century of development, the valve system is still in many respects the limiting factor in engine performance and life. The greater emphasis now being placed on fuel economy has not diminished the quest for improved performance for, clearly, reducing engine displacement while maintaining the capability to generate the desired level of power is a logical approach to lower fuel consumption. And if, in the process, the life of the engine can be extended such that the replacement rate of motor vehicles is reduced, the rate in which our mineral and total energy resources are depleted will also be reduced.
For the most part, current advances in valves and valve drive mechanisms are centered on improvements in poppet type valves which are mechanically actuated while being restrained by coil springs. Although refinements are being made to reduce erratic and detrimental motion at high engine speeds, it must still be tolerated to the point where there is danger of failure or excessive wear or where engine combustion processes are significantly degraded.
A lasting solution to this problem can only be in the form of a significant improvement. In this light, the solution offered by the inventor is the hydraulic actuation of the valves.